Dialysis: Osmosis and Diffusion Quiz

Dialysis: Osmosis and Diffusion

• The cell membrane is composed of a phospholipid bilayer, with polar heads facing outward and nonpolar tails facing inward.
• Nonpolar molecules can easily pass through the membrane, but polar molecules have difficulty.
• Water moves from a region of high water potential to a region of low water potential.
• The rate of diffusion is affected by factors like molecular size, polarity, solubility, and concentration gradient.
• Dialysis tubing acts as a model for the cell membrane, as it is also selectively permeable.
• A steep concentration gradient results in faster diffusion.
• Iodine turns blue-black in the presence of starch due to a chemical reaction.
• Osmosis is a type of diffusion where water moves across a semi-permeable membrane from a high concentration of water to a low concentration.
• The concentration of solutes and water potential are inversely proportional: higher solute concentration means lower water potential.
• Cells in a hypertonic environment shrink as water moves out of them due to a lower water potential outside the cell.
• Cells in a hypotonic environment swell as water moves into them due to a higher water potential outside the cell.
• Cells in an isotonic environment remain unchanged as the water potential inside and outside the cell is equal.
• The rate of diffusion decreases as molecular weight increases.
• Brownian movement, the random motion of particles, is driven by heat.

Enzyme Properties - Catalase Enzyme (Peroxidase)

• Enzymes are proteins made up of amino acids.
• Enzymes speed up reactions by lowering the activation energy required.
• The active site of an enzyme is the region where the substrate binds.
• Competitive inhibitors bind to the active site, while noncompetitive inhibitors bind to other sites on the enzyme.
• Guaiacol is an indicator for enzyme activity, turning from colorless to Amber brown when peroxidase is active.
• Saturation occurs when all available substrate or enzyme molecules are bound, leading to a plateau in the reaction rate.
• Nonprotein enzymes exist, but most are protein-based.
• Denaturation is the irreversible loss of enzyme structure and function.

Photosynthesis

• Chlorophyll a and chlorophyll b are primary photosynthetic pigments, while carotene and xanthophyll are accessory pigments.
• Chlorophyll absorbs light wavelengths used in photosynthesis and reflects unused wavelengths.
• Accessory pigments absorb a broader range of wavelengths than chlorophyll and transfer their absorbed energy to chlorophyll.
• Fluorescence occurs when electrons fall back to lower energy levels after being excited by light, releasing energy as photons.
• Chlorophyll fluorescence is red, while other pigments fluoresce in different colors.
• Photosynthesis requires carbon dioxide and produces glucose (a monomer) and oxygen.
• Pigments like chlorophyll are essential for photosynthesis as they capture light energy.
• During photosynthesis, light reactions produce ATP and NADPH, while dark reactions fix carbon dioxide into glucose.
• The Rf value (retardation factor) in chromatography is calculated by dividing the distance the pigment moved by the distance the solvent moved.
• Nonpolar pigments travel farthest along the chromatography paper due to their higher solubility in nonpolar solvents.
• The size and solubility of pigments determine their migration speed during chromatography.
• Contamination of chromatography paper with fingerprints can affect the migration of pigments.